We are very excited to release a revised (Second Edition) Guide to the Sea Urchin Reproductive Cycle and Staging Sea Urchin Gonad Samples.

This publication was first published in 2012 and is intended to be used as a guide for anybody with a need to understand, or an interest, in the reproductive cycle of sea urchins. It includes the following: a description of the reproductive cycle of sea urchins; the factors that cause variations in the size and quality of the gonad; methods for sampling sea urchin gonads; and a guide to reading the histology slides of sea urchin gonads in order to be able to classify them into the different stages of the reproductive cycle. In order to further assist with this process Appendix I show examples of histology slides taken from the two wild populations as well as histology slides from an enhanced captive sample. These clearly show the general pattern associated with the reproductive cycle of sea urchins but also the enormous variation that can occur between populations and treatments. This revised version has been improved and updated with scanning electron microscopy images as well as histology images of enhanced sea urchin roe. The authors hope that this guide will enable those working with sea urchins to follow the reproductive cycle of selected populations and that it will contribute to the knowledge of the reproductive cycle of sea urchins that occur in various populations around the coast of Norway and elsewhere around the world.